class_docstr: Test CLAVR-X Reader with Geo files.
docstr: Test exception raised when no donor file is available.
docstr_tok: ["Test","exception","raised","when","no","donor","file","is","available","."]
code: def test_no_nav_donor(self):
      """Test exception raised when no donor file is available."""
      import xarray as xr
  
      from satpy.readers import load_reader
  
      r = load_reader(self.reader_configs)
      with mock.patch("satpy.readers.clavrx.SDS", xr.DataArray):
          loadables = r.select_files_from_pathnames(
              [
                  "clavrx_H08_20180806_1800.level2.hdf",
              ]
          )
          r.create_filehandlers(loadables)
      with pytest.raises(
          IOError, match="Could not find navigation donor for"
      ):
          r.load(["variable1", "variable2", "variable3"])
  
imports: import os
  import unittest
  from unittest import mock
  import dask.array
  import numpy
  import pytest
  import xarray
  from pyresample.geometry import AreaDefinition, SwathDefinition
  from satpy.tests.reader_tests.test_hdf4_utils import FakeHDF4FileHandler
label_desc: Use image node_id 4 for calling the TestCLAVRXReaderGeo obj's underlying member method code with example usage: obj.test_no_nav_donor() without return types